Published online by Cambridge University Press: 07 August 2017
Evidence has been accumulating that the gas which produces the broad line emission (BLR gas) in active galaxies has a range of physical conditions, and may indeed come from a distribution of spatially distinct regions (Gaskell 1982, Ulrich et al. 1984, Netzer 1987, Collin-Soufrin et al. 1988). In this paper, we try to separate out any contribution to the BLR emission line profiles from optically thin material. We do this by comparing the profiles of OI λ8446 (a flourescence line only produced by clouds very optically thick to Lyman α, Elitzur and Netzer 1985) and Hα (which can be produced by optically thick and optically thin clouds).